Interlock switch



Nov. 29, 1955 A. J. HUcK ET AL INTERLOCK SWITCH 2 Sheets-Sheet l Filed May 3l, 1952 RIGHT BURNER OFF LOWMED HIGH HIGH MED LW OFF LEFT BURNER Nov. 29, 1955 A. J. HUcK ET AL 2,725,451

INTERLOCK SWITCH Filed May 5l, 1952 2 Sheets-Sheet 2 I y. l x

United States Patent 4,INTERLOCK SWITCH Alfred J. Huck and Israel Pass, St. kLous,-Mo., assignors to-Knapp-Monarch Company, St.fLouis, a corporationfof Delaware AApplication kMay 31, .1952, .Serial No. 291,044 -3`Claims. (Cl. 21920) ifhisinvention yrelates .to a switch for controlling a ,pluralityof electrical appliances Isuch Vas stove yplates or V,'thelikeiwherein parts oftwoswitches are so interlocked mechanicallythat ak maximum ,wattage isnotexceeded in ,any ypossible .combination :of .energization for .the diff/ene'nt `stove plates, yet `each one under certainfconditions canbeenergized-with morethan itsiproportionate share of thetotalcurrent available. i One object of the inventionisto provideia switchof .this .general ycharacter which is simple in construction andtfan be readily fabricated,-the assembledswitchbeing .comparatively inexpensive .and simple to connect into `circuits ofthe `stove plates and the number of terminals andcontacts being the least number possible for the stove plates controlledy by them, kthereby minimizing the num- ,berkof circuitlconnections between the switch structure ,and ,the heatingelernents ofP the stove plates.

IAnother object is tovprovide `apairof switches, one Ator `each stove plate, vwhich switches are `interlocked mechanically by engagement with each Yother so that upon .adjustment of one switch to asposition for maximum cur- ,rengsublsequent adjustmentof theother switch beyond ,its minimum current rposition will result in lretrograde in tsvorneiit kof the rst' swit'ch for.anintermediatecurrent 4value ofrtherirst stove plate, and subsequently further adjustment ofthesecond switch to its maximum current positionwill result in further retrograde movement of the ,rstnswitchto the .minimumvcurrent consumption posi- ,tio'lnfor its respective stoveplate.

A further object is toV provide a switchrstructure specitically designed for two heating units as in an electric hot `plate or the like ,wherein high, mediurrf and low 'heats can be provided forone burner and high,

` inediu1n and low Yheats may also `be provided for the `other burner, the two switches being sointerloelked, however, Vas to permit no more than .a medium-medium or high-low combination of the two burners as the maximum :available ycurrent supplytorjboth burners, and prevent jany possibilityrof either a fmedium-high or high-high adjustment. y v

MSztill'a `further object is toprovide an interlock switch structure including auminimumuof partsand Iterminals,

therebeing only tivev terminaison the switchfor four'heat ing elements of two stove plates 'and a line w ire,yand the labsolute minimum possible with respectto sets of cony-tacts (one set for each of lthe four heating elements),

with a single switch ,arm foreach switch capable of manual'adiustment and provided with means to vcoact with the contacts to separate and :engage them in a desired `.sequence `Ane additional object is to provide,.each switch with a detent detent notches .may-.be providevdfin the ibase member for the switchvstructure, the parts en- Ignn'neratedgrbeiug all that areinecessary for fully controlling the four heating elements in an interlocking arrangement that permits no more than a medium-medium or low-high adjustment for the respective burners.

With these and other objects in view, our invention consists infthe construction, Iarrangement and combinationofthe various partsof our interlockswitch, whereby .the `objects ,K contemplated lare attained, r`as ,hereinafter more fully ns et,forthpointed out inourclaims and illus- `trated in the ,accompanying drawings, `wherein:

Figure yl is a,bottom plan view of afportion of atwoburner hotplate showing a bottom planview of my interlock switch constructionwth ycertain portions insection to show 'details and with the,heatingelements of the burners ,shown diagrammatically.

Figure 2 is a frontelevation,ofthedialplate,forthe switch, as taken on the .line 2 f2,0f Figure llwhich cuts through the switch arms, Figure 2 showing them. insec tion.

Figure 3 is a sectional View on the line 3--3 of Figure 2.

Figure 4'is aperspective viewiofthe Aswitch structure showing it'inverted with respect to its position lin the stove; and

FiguresS, 6 and 7 are bottom plan '.viewsotheswitch ,showing respectively low-highmedium-mediumand highlow., positions ofy the switchesv for. the. left 'and ri ght. burners respectively. A

l-On the .accompanyingV drawings we'have used the reference numeraldlll toindicategthefhousing of an electric hotvvplatev and LB and-RBto indicate the-left and right burners thereof. These ,burners are provided with what yare usually termed lowfand medium heating elements .niediurnfRL for right-low.andflElM` for right-medium,

the heatingrelements being shown 4diagrammatically ,in Figure l.

`The leads `-from the heating elements extend to suitableterrninals l2, 14,1%, 5, 20 Land'F.Z'which are supported on-terminal'ibrackets 2d extending y downwardly .from the burners. in; the usu almaner land :suitablyi insulated therefrom. A linewirefLleXtendsfrom an outletplug -26 to. the :terminals 412. and d8.

yOurswitch structure includes ya substantially Vvtriangular .base 2-8 formed of sheet metalorthe like with ,a mounting flange 3) along one side-and the ilange 30.terminates :ina detent,.ange 32. `Thefilellltge Bills adapted to be fsecured `to the front wall-:34am thegfstove 'housing 10 as by rivets or bolts 36. It has a slot 38 therein through which vswitch arms iLfand `l extend. [The front wall 34.,.hasa slot `lzmatching the kslot-3,8 and a dial plate `42-is also secured-gto.theifront-wallby the bolts 36 iand .is `provided with .asimilarimatchingslot 44. This plate .as showndnPigure l2 may-be provided with suitable indicia ,to indicate .the left `,and right burners and the positions of the switch arm L and l in relationfthereto.

The inner ends sof thearms L and Rare pivotally ,mountedon va post 46 extending downwardly from the .base .plate 2S. ,Since the,p1ate28 is shown inverted in Figure 4, the post 46.,projects upwardly there rom. kMounted 4on the base,plate -23 .and .insulated 'therefrom `bya 4substantially `triangular ,sheet of insulation 4S `is @a terminalbracket 50 for a secondlinewire-LZ. :Con-

.tact springs S2and54A are vinounted thereon as by means ofrivets as illustrated and-,four contacts C1,:C2, C3 .and

f C4 Vare, carried therebyy for cooperation .withffourstationyary contacts LL,: RL. L`M and RM respectively. V,The stationary contacts ,are wired lto ...the :heating elements by, .meansv of wires, 56,7. 53, -59 i, and 2 60 respectively.

tions as the switch arms are moved to different positions. The switch arms are provided with handles 68 outside the dial 42 for convenience in manually moving them to their different possible positions.

The switch arms are adapted for interlocking by reason of engagement with each other and in order to tix the proper position of interlocking engagement one of them is provided with an interlock extension 70. It is shown extending from an elbow 72 of the arm R, this elbow being in circumferential alignment around the axis 46 with a similar elbow 74 of the arm L.

Detent mechanism for holding the switch arms in their different adjusted positions is provided in the form of detent notches 76 formed in the ilange 32 as illustrated and detent rollers 78 and 80 for cooperation therewith are carried by leaf springs 82 secured to the elbows 72 and 74.

Practical operation As shown in Figure l, the normal position of the right-hand switch lever R at off results in the roller 80 engaging in the outermost detent notch 76 at the right-hand end of the ange 32. In this position the pin 64 is holding the contact C1 widely spaced from the contact RM and the pin 63 in engagement with the cam node 66 holds the contact C2 spaced from the contact RL. The left-hand arm L has been moved from the oli position to the low position so as to permit the contact C3 to assume a position close to yet spaced from the contact LM while the pin 62 has disengaged the node 65 to permit C1 to engage LL'. Accordingly, the left-low heating element LL is the only one energized at this time, the circuit being traceable from L1 to L2 as follows: through 12, LL, 16, 56, LL', C', 52 and 50.

Assume now that it is desirable to energize the right burner for high heat (medium heating element RM plus low heating element RL). The right lever R may be moved from the off position to the high position as shown in Figure 5. Assuming further that the maximum allowable wattage for the lines L1 and L2 is 1650, the medium heating elements may each have approximately half this wattage, for instance, 824. The low heating elements would then desirably have a rating of about 412 watts so that the low plus high in Figure 5 would be low (412) plus high (824 plus 412) or 1648 watts.

If the left burner is now adjusted from low to medium, the arm L would be moved in the direction of the arrow 84 in Figure 6 and the elbow 74 would engage the interlock extension 70 and move the right switch arm R to its medium position also so that the two mediums (each 824 watts) would result in the maximum of 1648 watts.

Then if the arm L is moved further as indicated by the arrow 86 in Figure 7 to energize the left-hand burner LB for high heat, the right-hand burner will be automatically adjusted back to low heat so as to again get the same maximum wattage of 1648 as in Figure 5 except that the switch positions are reversed. Obviously movement of either R or L toward the other lever will result in the interlocking relation that moves such other lever in a retrograde direction to result in no more than a madium-medium or a high-low combination of energization for the two burners and the desired interlocking of the two switches is secured with a very simple mechanism having but very few parts and those parts being comparatively simple to assemble and electrically connect with the various heating elements.

Some changes may be made in the construction and arrangement of the parts of our interlock switch without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims any modilied forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

We claim as our invention:

1. In a switch structure for a pair of appliances each having a low and a medium heating element, a pair of switches, one for each heating appliance, each of said switches having first and second contacts adapted to correspond to the low and medium heating elements of the respective appliances, each of said switches being adjustable to three different circuit-energizing positions, said switches in each of said positions of adjustment being operative to close said contacts in different combinations, whereby in one combination of positions of said switches said first contacts are closed by each switch, in another combination the first contacts of the one switch and the second contacts of the other switch respectively are closed, in another combination the second contacts are closed by each switch, and in still another combination both the rst and second contacts are closed by the one switch while only the rst contacts are closed by the other switch, and a portion of one of said switches engaging a portion of the other to preclude any combination of positions of said switch for closing more than the rst contacts by the one switch when both the rst and second contacts are closed by the other switch.

2. In a switch structure for a pair of appliances each having a low and a medium heating element, a pair of switches, one for each heating appliance, each of said switches having iirst and second contacts, said first and second contacts of the one switch being adapted to correspond to the low and medium heating elements respectively of one of the appliances and the iirst and second contatcs of the other switch being adapted to correspond to the low and medium heating elements of the other of the appliances, each of said switches being adjustable to three diierent circuit-energizing positions to close said contacts in diterent combinations, a portion of one of said switches engaging a portion of the other to serve as an interlock between said switches, whereby when one of said switches is positioned so as to close both the first and second contacts the other of said switches can be moved only to its position for closing the rst contacts.

3. A switching system comprising four contacts for two pairs of circuits, a first switch lever for two of said contacts and a second switch lever for the other two of said contacts, said levers being pivotally mounted and swingable from an initial position of spaced-apart relation to each other to a position closely adjacent each other, interlock means carried by each of said levers and contactingly engaging when said levers are in closely adjacent relation, all of said contacts being open when said levers are in the initial position and successively closing when said levers approach each other for progressively energizing one, the other, and both of the circuits of each pair of circuits, said interlock means when engaged serving to eiect retrograde movement of the one switch lever back toward its initial position as the other switch lever is moved toward its position for closing both of said contacts, whereby when the one lever is positioned for closing both the first and second contacts the other lever can be moved only to its position for closingr the first contact.

References Cited in the iile of this patent UNITED STATES PATENTS 

